The present invention relates to radioactive waste pellets in solidified form and a process for forming the same. Particularly, the invention relates to radioactive waste pellets in solidified form which are recommended to be formed when the radioactive waste pellets include light waste pellets having specific gravities smaller than the specific gravity of a filler, and relates to a process for forming the same.
According to a known process, a concentrated waste liquor (consisting chiefly of sodium sulfate Na.sub.2 SO.sub.4) obtained by concentrating a regenerated waste liquor of used ion-exchange resin and a slurry of powdery ion-exchange resin, that are major radioactive wastes generated from boiling-water nuclear power plants, are dried, pulverized and pelletized, and the radioactive waste pellets thereof are charged into a container and are solidified with a filler.
For example, Japanese Patent Laid-Open No. 197500/1982 discloses a process according to which radioactive waste pellets are charged into a drum, and a solution of a sodium silicate composition that serves as a filler is poured into the drum, in order to seal the drum (page 5, right upper column, line 3 to left lower column, line 5 of the published specification).
The radioactive waste pellets may often include light waste pellets such as resin pellets having specific gravities smaller than the specific gravity of a filler, or may consist of light waste pellets only.
According to the above-mentioned process, when the solution of sodium silicate composition which serves as a filler is poured into a drum filled with the radioactive waste pellets, resin pellets having small specific gravities float and concentrate in the upper portion of the drum.
In this case, a layer consisting of the filler only is formed in the lower portion of the drum, and the filler is not sufficiently applied to the resin pellets that are radioactive waste pellets concentrated in the upper portion of the drum.
Therefore the filler is not uniformly applied to the radioactive waste pellets but is applied in a separated manner.
Since the filler is not uniformly applied to the radioactive waste pellets as mentioned above, the radioactive waste pellets are solidified very weakly. Further, since the radioactive waste pellets are not sufficiently charged to the lower portion of the drum, the volume of the solidified radioactive waste pellets cannot be effectively reduced.
Japanese Patent Laid-Open No. 73097/1975 discloses a container equipped with a cover which will be used for preparing radioactive waste pellets in solidified form (refer to the drawings of the published specification).
That is, it has been known to construct a container by providing a concrete cover for a concrete container which is impregnated with a polymeric monomer or a resin solution.
The above patent application, however, is concerned with the container only, but does not describe the radioactive waste pellets or the filler to be contained in the container. The above patent application does not teach to solidify radioactive wastes including light waste pellets having specific gravities smaller than that of the filler.